fix(cli): handle missing repo binding in register

[TrevorBasinger]

Summary

• handle the missing GLaaS repo binding path in roar register as a user-facing CLI error
• preserve the helpful guidance to link the repo to a TReqs owner/project or rerun with --public
• add regression coverage to ensure this path does not print a Python traceback

Testing

• uv run --extra dev ruff format roar/publish_auth.py roar/application/publish/service.py
  tests/integration/test_public_publish_intent_cli.py
• uv run --extra dev ruff check roar/publish_auth.py roar/application/publish/service.py
  tests/integration/test_public_publish_intent_cli.py
• uv run --extra dev pytest tests/integration/test_public_publish_intent_cli.py -q
• uv run --extra dev ruff check .
• uv run --extra dev mypy roar
• uv run --extra dev pytest -m "not live_glaas and not ebpf"

[christophergeyer]

🚢 it